isolate: Split UploadDeps into smaller chunks
isolate: Split UploadDeps into smaller chunks

BUG=692940

Review-Url: https://codereview.chromium.org/2983333002

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go